Compare Two PDF Files Online for Free
Upload two PDFs and see every difference highlighted side by side.
Original PDF
Drop original PDF
or browse
Modified PDF
Drop modified PDF
or browse
Compare PDF finds every difference between two versions of a document — a contract redline, two drafts of a report, a form before and after edits — and highlights exactly which words were added or removed, page by page. It extracts the text from both files and runs a word-level diff, so the result points to the actual wording that changed rather than making you scan both documents side by side looking for what's different.
What you can do
- A word-level comparison of two PDFs, page by page.
- Removed words are highlighted in red with a dashed outline, and added words in green.
- A summary of the total additions and deletions across the document.
How it works
- 1Drop the original file into the Original PDF dropzone.
- 2Drop the newer version into the Modified PDF dropzone.
- 3Click Compare PDFs.
- 4Review each page: removed words are highlighted in red with a dashed outline, added words in green.
- 5Check the summary above the pages for the total additions and deletions across the whole document.
Why use SmilingPDF for this
- The diff is word-level and position-aware, not just "these pages differ" — you see exactly which words changed.
- Removed text gets a dashed outline as well as a colour change, so the difference doesn't rely on colour alone.
- Both files are compared entirely in your browser; neither one is uploaded anywhere.
Private by design
Your file stays on your device.
- No upload
- No server storage
- No account required
- Browser-based processing
- No watermark
This tool runs inside your browser tab. Your file is read from your device, processed there, and handed back as a download — it is never sent to a SmilingPDF server, so there is nothing for us to store, read, or lose. You can check for yourself: open your browser's developer tools, switch to the Network tab and run the tool. Like most sites, SmilingPDF uses Google Analytics to count visits and which tools are used; that never includes the contents of your files. The privacy policy lists everything the site does collect.
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FAQ
Frequently asked questions
Got questions? We've got answers.
How does Compare PDF work?
We extract the text from both PDFs with position data, then run a word-level diff to find exactly which words were added or removed. Changed words are highlighted in red (removed from original) and green (added in modified) — removed words also get a dashed outline, so the difference doesn't rely on color alone. A summary above the pages totals every addition and deletion across the whole document.
Is my PDF uploaded to a server?
No. Everything is processed entirely in your browser. Your files never leave your device.
What if the PDFs have different page counts?
That's fine. If one PDF has more pages than the other, the extra pages are shown without a counterpart and counted as fully changed.
Why are some pages showing 0% changed even though content looks different?
The comparison is text-based. If the visible difference is purely visual (different fonts, image positions, colours) but the underlying text is the same, the change percentage will be 0%.
Can I compare scanned PDFs?
Scanned PDFs contain images rather than selectable text, so the text-based diff will find no differences. For scanned documents you would need OCR preprocessing first.